U.S. patent number 6,688,193 [Application Number 10/056,696] was granted by the patent office on 2004-02-10 for rotary blade cutterbar including plastic idler gear support hub with metal insert.
This patent grant is currently assigned to Deere & Company. Invention is credited to Gary Raymond Dustin, Michael James Mellin, Michael Joseph Verhulst, William Paul Wohlford.
United States Patent |
6,688,193 |
Wohlford , et al. |
February 10, 2004 |
Rotary blade cutterbar including plastic idler gear support hub
with metal insert
Abstract
A rotary cutterbar includes a gear case containing a
series-parallel set of gears including idler gears and pinion gears
for driving the cutting discs of the cutter units. The gear case
includes top and bottom walls and the idler gears are each received
on a hub including an enlarged upper end located in a hole provided
in the top wall and a threaded lower end screwed into a hole
provided in the bottom wall. The hubs each have a plastic outer
shell encasing a metal insert extending axially within the shell,
with the shell forming the sole contact between each hub and the
gear case whereby vibrations and shock loads respectively due to
gear tooth contact and a cutter knife contacting an obstacle are
absorbed by the shell to lessen the transmission of noise and the
magnitude of the impact force. O-ring grooves are provided in the
plastic shell and receive o-rings for preventing leakage from the
gear case through the holes in the top and bottom walls. The top
end of the metal insert is provided with an internal socket and an
external hexagonal surface, with the socket being provided for
receiving a complementary shaped wrench which is used for
installing the hub by screwing it into the threaded hole and with
the exterior surface providing a non-rotational surface to assist
in maintaining good physical retention of the insert within the
plastic shell.
Inventors: |
Wohlford; William Paul
(Bettendorf, IA), Dustin; Gary Raymond (Albia, IA),
Verhulst; Michael Joseph (Ottuma, IA), Mellin; Michael
James (Ottumwa, IA) |
Assignee: |
Deere & Company (Moline,
IL)
|
Family
ID: |
22006049 |
Appl.
No.: |
10/056,696 |
Filed: |
January 24, 2002 |
Current U.S.
Class: |
74/606R;
56/6 |
Current CPC
Class: |
A01D
34/664 (20130101); Y10T 74/2186 (20150115) |
Current International
Class: |
A01D
34/63 (20060101); A01D 34/66 (20060101); F16H
057/02 () |
Field of
Search: |
;74/66R,DIG.10
;56/6,10.3,13.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Fenstermacher; David
Claims
What is claimed is:
1. In a rotary mower cutterbar including a gear housing having
spaced apart top and bottom walls respectively provided with a
plurality of sets of axially aligned, upper and lower openings, a
gear train located between said top and bottom walls and including
a plurality of idler gears with each idler gear being located in
axial alignment with an associated set of said upper and lower
openings, an idler gear support hub supporting each of said idler
gears and including upper, intermediate and bottom sections with
the upper section being tightly received in said associated upper
opening, with the associated idler gear being rotatably mounted
said intermediate section being and with the lower section being
tightly received in said associated lower opening, the improvement
comprising: said hub having at least an exterior shell formed of
plastic of a thickness sufficient for dampening vibrations
generated by gear tooth engagement while isolating the vibration
from the remainder of the cutterbar, thereby reducing the
transmission of noise, and for dampening impact loads imposed on
said gear train for reducing the magnitude of the impact force,
thereby lessening the incidences of failures.
2. The rotary mower cutterbar defined in claim 1 wherein said hub
includes a metal insert encased in said plastic shell such as to
increase the shear strength of the hub.
3. The rotary mower cutterbar defined in claim 2 wherein said metal
insert has a non-circular cross section to assist in maintaining
good physical retention of the metal insert within the plastic
shell.
4. The rotary mower cutterbar defined in claim 1 wherein said upper
section of said hub is larger in diameter than said intermediate
section; said metal insert has an enlarged upper end located within
the enlarged upper section of the associated hub; and said enlarged
upper end of said metal insert being non-circular in cross section
to assist in maintaining good physical retention of the metal
insert within the plastic shell.
5. The rotary mower cutterbar defined in claim 4 wherein said
enlarged upper end of said metal insert is hexagonal is cross
section.
6. The rotary mower cutterbar defined in claim 1 wherein the
associated lower opening is a threaded hole; said lower section of
said hub is threaded; and said insert has an upper end provided
with a multi-faceted socket whereby a standard wrench may be used
to engage said socket and screw said hub into said threaded hole in
the bottom wall of the gear housing.
7. The rotary mower cutterbar defined in claim 2 wherein said
insert includes an axially extendng blind bore open to a top
surface of said hub which is provided for the purpose of receiving
a pin for positioning said insert in a mold operable for encasing
said insert in said plastic shell.
8. The rotary mower cutterbar defined in claim 1 wherein said
insert has a length substantially equal to that of said shell.
9. A hub adapted for rotatably supporting a gear in a gear housing
between top and bottom metal walls, comprising: a top and bottom
sections respectively adapted for fitting tightly into a pair of
axially aligned openings respectively provided in the top and
bottom metal walls; and at least an exterior shell formed of
plastic of a thickness sufficient for dampening vibrations
generated by gear tooth engagement thereby isolating the vibration
from the top and bottom walls so as to reduce the transmission of
noise and for dampening impact loads imposed on the supported gear
for reducing the magnitude of the impact force and, hence, the
incidences of failures.
10. The hub defined in claim 9 wherein a metal insert is encased in
said plastic shell such as to increase the shear strength of the
hub.
11. The hub defined in claim 10 wherein said metal insert has a
non-circular cross section to assist in maintaining good physical
retention of the metal insert within the plastic shell.
12. The hub defined in claim 9 wherein said top section is larger
in diameter than an intermediate section; and said metal insert
having an enlarged upper end located within the top section; and
said enlarged upper end of said metal insert being non-circular in
cross section to assist in maintaining good physical retention of
the metal insert within the plastic shell.
13. The hub defined in claim 12 wherein said enlarged upper end of
said metal insert is hexagonal is cross section.
14. The hub defined in claim 9 wherein said bottom section is
threaded and adapted for being installed in an associated lower
opening when the latter is threaded; and said insert has an upper
end provided with a multi-faceted socket whereby a standard wrench
may be used to engage said socket and screw said hub into said
threaded hole in the bottom wall of the gear housing.
15. The hub defined in claim 9 wherein said insert includes an
axially extending blind bore open to a top surface of said hub
which is provided for the purpose of receiving a pin for
positioning said insert in a mold operable for encasing said insert
in said plastic shell.
16. The hub defined in claim 9 wherein said insert has a length
substantially equal to that of said shell.
Description
BACKGROUND OF THE INVENTION
The present invention relates to rotary blade cutterbars and more
particularly relates to support hubs for the idler gears of such
cutterbars.
Rotary blade cutterbars have a plurality of side-by-side cutting
units with the cutter discs of some cutterbars having gear pinion
gears driven through a gear train comprising a plurality of meshed
idler gears. These idler gears are meshed with each other so as to
transmit power from one end to the other of the cutterbar and are
selectively meshed with the pinion gears of the cutting units for
determining the direction of rotation of the cutting units. The
support hubs for the idler gears of one known cutterbar of this
type are fabricated from steel and include o-ring grooves in which
o-rings are placed to seal the interfaces of the hub with the gear
box. These hubs experience very high shear loads at times when the
cutting blades of the cutter units impact foreign objects in the
field. Also, the current cutterbar transmits gear vibrations to the
implement through its rigid structure and is heavy. U.S. Pat. No.
5,715,662, granted to Walters on Feb. 10, 1998 discloses a
cutterbar of this type.
SUMMARY OF THE INVENTION
According to the present invention there is provided an improved
rotary blade cutterbar of the type including a plurality of cutting
units having pinion gears driven through a train of meshed idler
gears, and more particularly there is provided improved hubs for
mounting the idler gears.
An object of the invention is to provide a rotary blade cutterbar
having idler gears with supporting hubs that are relatively light
weight while being capable of dampening gear vibrations.
Another object of the invention is to provide idler gear supporting
hubs, as set forth in the previous object, which are lower in cost
than current idler gear supporting hubs yet strong enough to
withstand high shear loads.
A specific object of the invention is to provide idler gear
supporting hubs, as set forth in the previous objects, wherein the
hubs are constructed of a molded plastic material.
Still a more specific object of the invention is to provide idler
gear supporting hubs as set forth in the immediately preceding
object wherein the hubs are each strengthened by a metal
insert.
These and other objects of the invention will be apparent from a
reading of the ensuing description together with the appended
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a portion of a cutterbar of the type
with which the present invention is particularly adapted for
use.
FIG. 2 is an enlarged vertical sectional view taken at 2--2 of FIG.
1.
FIG. 3 is a top plan view of one of the housing sections making up
the cutterbar of FIG. 1.
FIG. 4 is a view of the molded plastic, idler gear support hub of
the present invention.
FIG. 5 is a view of the metal insert that is molded into the center
of the plastic hub shown in FIG. 4.
FIG. 6 is a head end view of the metal insert shown in FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Preliminarily, it should be noted that terms used herein such as
"right", "left", "forward", "front", "rearward" and "rear" are with
reference to an observer standing behind the structure and facing
in the normal direction of forward movement of the structure during
its operation.
Referring now to FIG. 1, there is shown a left end segment of a
rotary or disc mower cutterbar 10 constructed of a plurality of
interconnected hollow housing modules 12 which cooperate with each
other and with left and right end caps (only left end cap 14 being
shown) to form a fluid tight gear housing 16. A stiffener beam 18
is secured across a rear side of the housing 16. Each of the
modules 12 has a rotary cutting unit 20 mounted to a central
location thereof for being driven by a series-parallel spur gear
drive train, with the left-most housing module 12 containing a
power input pinion gear 22 and with the remaining modules 12 each
containing a pinion gear 24
The cutterbar 10 is powered, for example, from a power take-off of,
or fluid motor coupled to the hydraulic system of, a prime mover
(not shown), the power entering the cutterbar 10 by way of an input
power drive shaft 26 integral with and projecting upwardly from the
power input pinion gear 22. Referring now also to FIG. 2, it can be
seen that power is transferred from the input pinion gear 22 to the
pinion gears 24, and hence, to cutting unit drive shafts 28, formed
integrally with the pinion gears 24, by a plurality of intermeshed
idler gears 30 extending across a rear zone of the housing 16. The
gear housing modules 12 are each designed for having a pair of the
idler gears 30 mounted inside, however, it is noted that only one
idler gear is required for the right- and left-most modules 12 of
the cutterbar 10. However, in all cases, a pair of idler gear
support hubs 32 is associated with each module 12.
As can best be seen in FIG. 3, each of the housing modules 12
includes a central forward opening 34, located in an elevated
central top wall portion 36, and identical right- and left-hand
rear openings 38 and 40, respectively, located in a horizontal rear
wall portion 42 of the module 12 and spaced equidistant from the
forward opening 34 and from a longitudinal center line passing
through the opening 34 and between the openings 36. Located in a
bottom wall 44 of the housing module 12 respectively in axial
alignment with the pair of openings 38 and 40 are right- and
left-hand threaded holes 46 and 48. The holes 46 and 48 are located
in respective domed areas 50 of the bottom wall 44 with a top of
each area 50 defining an upwardly facing bearing seating surface
52.
Each idler gear 30 has the outer race of a ball bearing 54 tightly
received in a central bore thereof and held in place by a snap ring
57 which is received in complimentary grooves located in the gear
and outer bearing race. The idler gears 30 are positioned within a
cavity 58 defined in part by, and located between, the top wall
portion 42 and the bottom wall 44 of the selected housing module 12
with the inner race of the associated bearing 54 engaging the
seating surface 52 of the associated domed area 50.
With reference to FIG. 2 and also to FIGS. 4-6, it can be seen that
the idler gear mounting hub 32 includes an enlarged upper head
section 56 tightly received in the circular opening 38, a middle
section 58 having a diameter less than the head section and being
tightly received in the inner race of the bearing 54 and a lower
end section 60 having a diameter less than that of the middle
section and being threaded and screwed into the threaded hole 46.
The head section 56 defines a downwardly facing surface engaged
with a top surface of the inner race of the bearing 54. The hub 42
is preferably constructed so as to include an outer shell 62 (FIG.
2) molded from a polymeric plastic material. The head section 56
and the lower end section 60 are respectively provided with annular
grooves receiving respective o-ring seals 64 and 66 for preventing
the leakage of gear train lubricant and for excluding dust from the
cavity 58. Obviously, the hub 32 could be molded so as to include
integral annular ribs for forming seals instead of the o-ring
grooves and o-rings 64 and 66.
Molded as an integral part of the hub 32 is a metal insert 68 which
is located within and along the central axis of the plastic shell
62. The insert 68 has a length commensurate with that of the shell
62 and is provided for adding shear strength to the hub, although
in some conditions a solid plastic hub would have the required
strength for satisfactory operation. The insert 68 has an enlarged
head-like upper end section 70 provided with a hexagonal exterior,
which maintains good physical retention of the insert in the
plastic shell 62, and a hexagonal interior surface forming a socket
72 which may be engaged by a wrench to aid in installing and
removing the hub 70. A blind bore 74 extends axially in the insert
68 and serves during the molding process to hold the insert in a
desired position on a pin located in the mold.
When a cutterbar 10 equipped with a plurality of the hubs 32 is
working in the field, the low modulus plastic shells 62 of the hubs
70 will in be the path of the transmitted vibrations from the gear
tooth engagement of the input pinion gear 22 and pinion gears 24
with the idler gears 30 to the housing made up of the modules 12,
which makes up the major portion of the mass of the cutterbar.
Thus, these vibrations will be dampened with the result that noise
transmission will be lessened. Also, in the event that the cutting
blades or other exterior elements of one or more of the cutting
units 20 should come into contact with an obstacle, the low modulus
plastic material of shells 62 of the hubs 32 will deform during the
shear load experienced due to the impact and will lengthen the time
of deceleration of the rotating mass so as to reduce the magnitude
of the impact force, thereby reducing the incidences of failure.
The metal insert 68 increases the shear strength of the associated
hub 32.
Also, it is to be noted that because the hubs 32 are partially
composed of plastic, the weight of the cutterbar 10 is reduced
which reduces the moment of inertia of the cutterbar so as to
reduce the vertical movement of the cutterbar and its suspension
during operation, thereby improving the cutting performance of the
implement. Furthermore, due to the hubs 32 being suited to high
volume molding operations, a cost reduction is realized.
* * * * *